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Atomic-scale engineering of future high-k dynamic random access memory dielectrics

The example of partial Hf substitution by Ti in BaHfO3
 
: Dudek, P.; Lupina, G.; Kozowski, G.; Zaumseil, P.; Bauer, J.; Fursenko, O.; Dabrowski, J.; Schmidt, R.; Lippert, G.; Müssig, H.-J.; Schroeder, T.; Schmeißer, D.; Zschech, E.

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Journal of vacuum science and technology B. Microelectronics and nanometer structures 29 (2011), Nr.1, Art. 01AC031, 7 S.
ISSN: 0734-211X
ISSN: 1071-1023
ISSN: 2166-2746
ISSN: 2166-2754
Workshop on Dielectrics in Microelectronics (WoDiM) <16, 2010, Bratislava>
Englisch
Zeitschriftenaufsatz, Konferenzbeitrag
Fraunhofer IZFP, Institutsteil Dresden ( IKTS-MD) ()

Abstract
Controlled substitution of Hf4+ by Ti4+ ions in thin BaHfO3 was investigated in view of future dynamic random access memory (DRAM) applications. The 50% substitution of Hf ions reduces the crystallization temperature by about 200 °C with respect to BaHfO 3 layers making the BaHf0.5 Ti0.5 O3 layers compatible with DRAM processing. The resulting cubic BaHf0.5 Ti0.5 O3 dielectrics show k90 after rapid thermal annealing at 700 °C which is three times higher than for BaHfO3 at similar temperatures. Leakage current values of 4× 10-5 A/ cm2 at 0.5 V for Pt/ BaHf0.5 Ti0.5 O 3 /TiN capacitors with capacitance equivalent thickness <0.8 nm are achieved. Synchrotron-based photoelectron spectroscopy in combination with nanoscopic conductive atomic force microscopy measurements reveals that the use of high work function electrodes and homogeneous film deposition techniques is crucial for controlling the leakage current.

: http://publica.fraunhofer.de/dokumente/N-189930.html